GIFT  OF 


• 


ARMY  AIRPLANE  GLIDING  TO  NORTH  ISLAND  OVER 
U.  S.  CRUISER  "SAN  DIEGO" 


The  Aviator  and  the 
Weather  Bureau 


BY 

FORD  A.  CARPENTER,  LL.D. 


METEOROLOGIST 


ILLUSTRATED  WITH  PHOTOGRAPHS  AND  CHARTS 
BY  THE  AUTHOR  AND  OTHERS 


PUBLISHED  BY  THE 

SAN  DIEGO  CHAMBER  OF  COMMERCE 
1917 


Published  by  permission 
Dated  August  25,  1916 


Second  edition,  5,000  copies 

;; 


^\^ 

••  -    :    •  : 


J.  Horace  McFarland  Company 

Mt.  Pleasant  Press 
Harrisburg,  Pennsylvania 


OP, 


Introductory  Note 

THIS  is  a  brief  but  general  account  of  the  history 
of  aviation  as  it  is  associated  with  southern 
California,  a  description  of  the  War  Depart- 
ment school  of  aviation  at  San  Diego,  a  syllabus  of 
the  course  of  lectures  delivered  there  on  the  subject 
of  practical  meteorology  as  applied  to  aviation,  a 
narrative  of  weather-study  from  an  airplane,  and  a 
recital  of  subsequent  active  cooperation  between  the 
aviators  and  the  U.  S.  Weather  Bureau.* 

Much  of  the  material  in  the  following  pages  was 
obtained  by  the  writer  while  detailed  as  Lecturer  in 
Meteorology  to  the  Signal  Corps,  War  Department 
Aviation  School  at  San  Diego,  in  1915-1916,  also 
when  detailed  in  the  same  official  capacity  to 
the  U.  S.  Army  Military  Training  Encampment, 
Monterey,  1916;  and  at  the  summer  sessions  of  the 
University  of  California  during  1914-1916. 

Los  ANGELES,  CAL., 
February,  1917. 

t  *It  may  be  remembered  that  the  weather  service  of  the  United  States 
originated  with  the  Signal  Corps  of  the  Army  and  that  the  Weather 
Bureau  was  created  from  it  by  Act  of  Congress,  June,  1891,  and  made  a. 
bureau  of  the  U.  S.  Department  of  Agriculture.  As  a  former  member  of 
the  Signal  Corps  the  writer  enjoyed  the  renewal  of  old  friendships  among 
the  officers  at  the  Aviation  School.  Col.  W.  A.  Glassford,  Signal  Corps, 
U.  S.  Army,  Commandant  of  the  War  Department  Aviation  School  at 
San  Diego,  kindly  read  the  manuscript  of  the  following  pages  and  the 
writer  gratefully  acknowledges  his  valuable  suggestions. 

(3) 

3597j . 


To 
J.  S.  A. 


Table  of  Contents 


CHAPTER  I 

The  Signal  Corps  Aviation  School  at  San  Diego, 
California 7 


CHAPTER  II 
Applied  Meteorology  for  the  Aviator      .       .       .11 

CHAPTER  III 
Weather  Observations  from  an  Airplane        .       .16 

CHAPTER  IV 
Investigating  the  Upper  Air 25 


(5) 


List  of  Plates 

Figure 
No.  Page 

Army  airplane  gliding  to  North  Island  over  U.  S. 
Cruiser  "San  Diego" Frontispiece 

1.  Congressional  Medal  awarded  Wright  brothers       .    .  33 

2.  Ascent  of  sounding  balloons  at  Avalon 34 

3.  Meteorograph  which  made  the  ascent  of  July  27,  1913  35 

4.  First  flight  of  airplane  carrying  two  persons    ....  36 

5.  Sub-station  at  Mount  Wilson  Observatory 37 

6.  Type  of  airplane  used  in  1911  on  North  Island       .    .  38 

7.  Discussing  a  flight 39 

8.  Captain  Culver  and  parachute  for  determining  wind- 

direction     40 

9.  Lieutenant  Gorrell,  U.  S.  Infantry,  as  observer  ...  41 

10.  Point  Loma  from  the  eastern  shore  of  North  Island  .  42 

1 1.  San  Diego,  across  Spanish  Bight,  from  U.  S.  Aviation 

School,  at  twilight 43 

12.  Instructor  Brindley  and  Meteorologist  Carpenter  in 

Military  Tractor  No.  50 44 

13.  Military  Tractor  No.  50 45 

14.  "Trimming"  Tractor  No.  50       46 

1 5 .  Military  Tractor  No.  50  just  before  leaving  the  grOu nd  47 

1 6.  San  Diego  harbor  at  over  two  thousand  feet  altitude  48 

17.  San  Diego  viewed  from  an  altitude  of  thirty-five 

hundred  feet 49 

1 8.  Military  Tractor  No.  50  viewed  from  the  ground  .    .  50 

19.  Flying  Squad's  Wind  Direction  Pennant  Tower     .    .  51 

20.  The  Aviation  School  Motor-Boat  "Pronto"     ....  52 

21.  U.  S.  Aviation  Field  at  three  thousand  feet  altitude    .  53 

22.  Repair  Shop,  U.  S.  Aviation  School,  San  Diego,  Cal.  .  54 


(6) 


The  Aviator  and  the 
Weather  Bureau 


CHAPTER  I 

THE  SIGNAL  CORPS  AVIATION  SCHOOL  AT 
SAN  DIEGO 

History. — The  year  1911  marked  the  beginning 
of  the  United  States  aviation  school  at  San  Diego. 
There  is  no  finer  tribute  to  the  equability  and  general 
excellence  of  the  climate  of  southern  California  than 
that  given  in  the  history  of  aeronautics.  It  was  here, 
in  1900,  that  Chanute  completed  his  early  and  epoch- 
making  observations  of  the  flight  of  gulls  and  peli- 
cans. These  contributed  largely  to  the  success  of 
the  Wright  brothers  a  few  years  afterward.  It  was 
in  southern  California,  six  years  ago,  that  Harkness, 
in  an  Antoinette,  made  his  record  monoplane  flight 
to  Tia  Juana.  San  Diego  witnessed  the  flying  of  the 
first  seaplane,  by  Curtiss,  five  years  ago.  It  is  in 
this  district  that  not  only  the  War  Department 
aviation  school  and  a  number  of  commercial  flying 
schools  are  located,  but  also  one  of  the  large  air- 
plane* factories  in  this  country. 

Location  of  the  School. — Whatever  the  final  action 
may  be  as  to  permanent  location,  it  has  been  con- 

*The  National  Advisory  Committee  for  Aeronautics  in  its  report  of 
October  17,  1916,  on  Nomenclature  for  Aeronautics,  the  name  airplane  is 
substituted  for  "Any  form  of  aircraft  heavier  than  air  which  has  wing 
surfaces  for  sustention,  with  stabilizing  surfaces,  rudders  for  steering,  and 
power-plant  for  propulsion  through  the  air." 

(7) 


8         The  Aviator  and  the  Weather  Bureau 

ceded  by  all  authorities  that  the  situation  of  the 
aviation  school  on  North  Island,  San  Diego  Bay,  is 
ideal.  (See  Fig.  2 1 .)  The  so-called  island  is  connected 
with  the  peninsula  of  Coronado  by  a  narrow  sand- 
spit,  and  it  comprises  many  hundred  acres  of  level 
land  free  from  buildings  and  any  sort  of  overhead 
wires.  The  island  fronts  the  ocean  on  the  south; 
Point  Loma  on  the  west  with  the  narrow  entrance  to 
the  bay  between;  to  the  north  is  the  city  of  San 
Diego  across  the  bay;  and  Coronado  just  beyond 
Spanish  Bight  on  the  east.  This  natural  arrange- 
ment gives  good  air  conditions  for  beginners,  and 
also  enables  them  to  use  the  smooth  waters  of  the 
bay  as  well  as  the  rough  ocean  water  for  the  sea- 
planes. The  proximity  of  this  location  to  San  Diego 
is  also  a  distinct  advantage.  (See  Fig.  n.)  All  of 
the  structures  of  the  aviation  school  on  North  Island 
are  temporary,  the  buildings  consisting  of  a  scatter- 
ing array  of  huge  sheds. 

Character  of  Instruction. — Officers  from  all 
branches  of  the  army  volunteer  for  this  service.  The 
qualifications  of  an  aviator  are  caution,  judgment, 
and  technical  skill.  Deficiencies  in  caution  and 
judgment  being  temperamental  are  rarely  remedied, 
while  technical  skill  is  largely  a  matter  of  acquire- 
ment. Less  than  ninety  days  are  allowed  for  quali- 
fication as  a  junior  aviator,  and  if  in  that  period  the 
officer's  deficiencies  are  found  to  be  inherent,  he 
returns  to  his  company. 

The  school  is  a  place  for  hard  work  and  quick 
thinking.  Detail  in  the  repair  shop  is  part  of  the 
course,  as  is  also  the  use  of  the  gasoline  engine  in 
motor  trucks  as  well  as  in  aircraft.  (See  Fig.  22.) 
Theory  and  practice  are  closely  united :  the  former  is 


Signal  Corps  Aviation  School  9 

carried  on  by  means  of  bi-daily  lectures,  while  the 
early  morning  hours  are  devoted  to  flying.  Pilot- 
and-observer  machines  equipped  with  double  control 
are  used  in  instruction.  The  aviation  instructor 
ascends  with  the  student  and  allows  him  to  manipu- 
late the  controls,  only  resuming  the  management  of 
the  airplane  in  an  emergency.  Needless  to  say,  the 
life  of  an  instructor  is  a  most  hazardous  one  and  full 
of  thrills.  His  duty  is  to  be  on  the  alert  to  correct 
errors  in  the  manipulation  of  the  machine.  After 
every  trip  the  instructor  reviews,  point  by  point,  the 
features  of  the  flight,  showing  the  pupil  his  deficien- 
cies and  explaining  how  he  may  avoid  them  in  the 
future.  The  instruction  is  terse  but  kindly,  and  the 
manner  of  imparting  this  information  leaves  nothing 
to  the  imagination.  After  watching  student  and 
instructor,  and  closely  studying  the  finished  work  of 
an  aviator,  it  is  my  opinion  that  in  no  other  occupa- 
tion must  there  be  such  perfect  coordination  between 
mind  and  muscle:  the  perfectly  qualified  aviator  is 
the  modern  super-man.* 

Results  of  a  Year's  Work. — During  the  year  1915, 
the  students  of  the  aviation  school  made  3,652 
flights  with  a  total  time  aloft  of  1,516  hours,  and  a 
mileage  of  95,000.  As  regards  weather  conditions 
affecting  flights,  it  will  be  found  interesting  to 
note  Chart  No.  5  giving  number  of  flights  and  dur- 
ation for  the  fourteen  months  ending  August,  1916, 
which  shows  that  work  progressed  regardless  of 

*The  army  aviator  of  today  is  picked  for  his  quickness  of  mind  and 
body,  and  the  first  thing  that  strikes  you  about  him  is  a  sort  of  feline, 
wound-up-spring  alertness.  Then  you  note  his  reticence,  the  cool  reserve 
of  a  man  whose  lot  is  to  express  himself  in  deeds  rather  than  words.  And, 
lastly,  there  is  the  quiet  seriousness,  verging  almost  on  sadness,  of  a  man 
who  must  hold  himself  ready  to  look  death  between  the  eyes  at  any 
moment  and  yet  keep  his  mind  detached  for  other  things. — Lewis  R. 
Freeman  in  the  Atlantic  Monthly. 


io       The  Aviator  and  the  Weather  Bureau 

weather,  and  at  an  increasing  rate.*  In  February,  a 
military  tractor-seaplane  (an  all-California  product), 
125-horsepower  motor,  with  twenty-six  gallons  of 
gasoline,  four  gallons  of  oil,  and  three  passengers, 
making  a  total  weight  of  3,100  pounds,  reached  an 
altitude  of  12,362  feet.  This  was  the  world's  record, 
the  previous  altitude  under  the  same  conditions 
having  been  9,000  feet. 

*"It  is  estimated  that  the  average  cost  to  France  of  training  each 
pilot  is  five  thousand  dollars  ...  no  less  than  from  four  to  six  months 
are  devoted  to  the  training  of  finished  pilots.  Although  I  have  just  come 
from  France,  the  progress  of  aviation  is  so  rapid  that  much  of  my  own 
knowledge  may  be  out  of  date  before  I  again  return  to  the  front." — 
C.  D.  Winslow,  "With  the  French  Flying  Corps,"  1917,  4-5: N.  Y. 


CHAPTER  II 
APPLIED  METEOROLOGY  FOR  THE  AVIATOR 

Activities  of  the  Weather  Bureau  in  Relation  to 
Aeronautics. — Naturally  the  progress  of  aerial  navi- 
gation has  at  all  times  been  rather  closely  connected 
with  the  Weather  Bureau.  For  over  a  decade  the 
Bureau  has  not  been  content  with  surface  observa- 
tions but  has  maintained  laboratories  for  the  study 
of  the  upper  air.  The  results  of  its  observations  are 
considered  a  mine  of  information  for  the  student 
aviator.  Prof.  Charles  F.  Marvin,  the  Chief  of  the 
Weather  Bureau,  is  a  member  of  the  National 
Advisory  Committee  for  Aeronautics,  and  chairman 
of  a  subcommittee  engaged  on  the  determination  of 
the  problems  of  the  atmosphere  in  relation  to  aero- 
nautics.* 

The  first  official  cooperation  between  the  Weather 
Bureau  and  the  War  Department  aviation  school 
was  inaugurated  in  the  year  1914  by  Dr.  W.  J. 
Humphreys,  Professor  of  Meteorological  Physics, 
when  he  was  detailed  to  give  a  course  of  lectures.  It 
was  during  this  course  that  he  lectured  on  "Holes  in 
the  Air."f  This  paper  has  been  reprinted  as  a  text- 
book for  the  aviation  school. 

Early  Studies  in  Aeronautics. — Unofficially,  how- 
ever, the  cooperation  extended  back  some  fifteen 
years  prior  to  that  time,  when  the  writer  was  in 
charge ^of  the  local  office  of  the  Weather  Bureau  at 
San  Diego,  and  assisted  the  aeronautical  engineer, 

*MonthIy  Weather  Review,  1915,  32:500,  Washington. 
fPopuIar  Science  Monthly,  1914,  44:18-34,  N.  Y. 

(II) 


12       The  Aviator  and  the  Weather  Bureau 

Octave  Chanute,  in  his  observations  and  experiments 
on  San  Diego  Bay.*  At  this  time  hundreds  of  photo- 
graphs of  sea-gulls,  pelicans,  and  other  soaring  birds 
were  made,  and  both  birds  and  photographs  studied 
and  analyzed.  Ever  since  then  more  or  less  interest 
has  been  taken  by  the  writer  in  aerial  navigation. 
During  an  assignment  to  the  Central  Office  the  work 
of  the  Wright  brothers  was  observed  and  studied. 
The  association  with  the  late  Octave  Chanute  and 
his  friends,  the  Wrights,  during  their  experimental 
flights  at  Fort  Meyer,  Virginia,  in  September,  1908, 
is  counted  among  the  many  pleasant  memories  of 
the  Washington  visit.  It  was  here  that  was  witnessed 
the  first  flight  with  a  passenger  (see  Fig.  4),  Mr. 
Orville  Wright  taking  up  with  him  Major  (now 
Colonel)  George  O.  Squier,  the  present  head  of  the 
aviation  branch  of  the  army.  Such  was  the  infancy 
of  the  flying-machine  that  at  that  date  no  fatalities 
had  occurred.  A  few  years  later  the  writer  had  the 

Pleasure  of  accompanying  Mr.  Glenn  Curtiss  while 
e  was  determining  a  site  for  his  school,  which  was 
finally  located  on  North  Island.  (See  Fig.  6.) 
Shortly  afterward,  from  this  place,  Harry  Harkness 
made  record  amateur  cross-country  flights  in  an 
Antoinette  monoplane. 

Active  Work  of  the  Weather  Bureau. — During  the 
score  of  years  that  the  writer  has  been  in  charge  of 
the  San  Diego  and  Los  Angeles  stations  of  the 
Weather  Bureau,  interest  in  flying  has  been  cumu- 
lative. Efforts  have  been  made  to  furnish  aviators 
with  available  data  so  that  at  the  present  time  a  day 
seldom  passes  without  conference  with  officials  or 

*"CIimate  and  Weather  of  San  Diego,  "Carpenter,  1913,  57-59.  San 
Diego. 


Applied  Meteorology  /or  the  Aviator       13 

students  of  Government  or  private  flying  schools  in 
this  vicinity. 

Lectures  on  Meteorology  as  Applied  to  Aviation. — 
Through  the  War  Department,  October,  1915,  on 
request  of  the  commanding  officer  of  the  Signal 
Corps  aviation  school,  at  San  Diego,  the  writer  was 
directed  by  the  Chief  of  the  Weather  Bureau  to 
deliver  two  lectures  of  which  the  following  are  out- 
lines: 

"What  the  Weather  Bureau  Offers  the  Aviator" 

(Illustrated  by  37  lantern-slides  from  photographs  by  the  author) 

Introductory: 

Weather  service  once  part  of  the  Signal  Corps,  U.S.A. 
Transfer  in  1891  to  the  Department  of  Agriculture. 

Distribution  of  weather  stations  in  the  United  States: 
Character  of  data  obtainable: 

Advance  data  from  the  daily  map  such  as 

Position  of  high  and  low  areas. 
Weather  conditions  from  sub-stations  in  vicinity. 

The  weather  map: 
How  constructed. 
How  distributed. 

Specimen  maps  showing  differing  conditions  in  California. 
Winds,  velocity  and  frequency: 
On-shore. 
Off-shore. 

Discussion  of  air  conditions  December  20-22,  1914. 
The  international  weather  map. 
Relation  to  weekly  forecasts. 

Cardinal  climatic  features: 

Ascending  winds  and  types  producing  them: 

Cloud,  fog,  precipitation. 
Descending  winds: 

"Northers"  and  dust-storms. 

Thermograph  and  hygrograph  traces. 


14       The  Aviator  and  the  Weather  Bureau 

Factors  in  the  meteorology  of  southern  California: 
Influence  of  latitude: 

Sea. 

Mountains. 

Desert. 

Path  and  distribution  of  storm  areas. 
Knowledge  of  local  climatology  necessary  in  flying. 
Local  winds  discussed: 

"Woollies"  (descending  wind  eddies). 

"Chubascos"  (south  coast  thunder  squall). 

"Santa  Anas"  (northeasterly  and  desiccating). 

"Wilmingtons"  (northwesterly  line-squall). 

"Practical  Meteorology  for  the  Aviator" 

(Illustrated  by  72  lantern-slides  from  photographs  by  the  author) 

Historical: 

Original  work  begun  in  Scotland,  year  1749. 
Characteristics  — 

English  work;  Dines*  minute  meteorograph. 
French  work;  Dr.  Berson's  balloon  ascent  of  6^  miles. 
German  work;  detailed  data  in  low  altitudes. 
American  work  began  with  Franklin. 
The  Upper  Air: 
Definition  : 

"Stratosphere"  is-  (according  to  some   authorities)    the 
dynamical  laboratory  of  the  atmosphere  where  the 
main  causes  of  pressure  originate. 
Results  in  America: 

Balloon  meteorograph  (Fig.  3). 

Charts  showing  rate  of  increase  in  wind  velocity  with 

elevation  (Chart  No.  4). 
Wind,  temperature,  pressure,  humidity  at  maximum  air- 

plane height  of  26,242  feet. 
Stratosphere: 

Lower  level  in  winter  than  in  summer. 

Lower  temperature  in  summer  when  surface  pressure  is 


. 
Definition  : 

"Troposphere"  is  the  physical  laboratory  where  cloud 


Conditions  within  6  or  7  miles 


Applied  Meteorology  for  the  Aviator       15 

Clouds  and  their  Meaning: 
Cirrus: 

Height  and  composition. 
Formation: 

Perpendicular  shafts  of  clouds  indicate  rapid  changes 

in  weather. 

Horizontal  layers,  no  change  and  clouds  will  dissipate. 
Cirro-stratus,  threatening  in  winter. 
Cirro-cumulus,  fair  and  foul  varieties  differentiated. 
Cumulus  with  strong  uplift. 
Alto-cumulus,  cause  of  parallel  rows. 
Fracto-cumulus,  wind  indicator,  Point  Loma  "woolly." 
Stratus. 

Alto-stratus,  favorable  for  flying. 

Strato-cumulus,  long  shallow  rolls,  threatening  in  winter. 
Cumulo-nimbus,  unsafe  air  conditions  for  flying. 
Fracto-nimbus,  waterspouts  and  their  causes. 
Velo  cloud,  examples,  cause,  effect,  distribution,  density. 
Fog,  examples  of  great  fog-belts. 


CHAPTER  III 

NARRATIVE  OF  WEATHER  OBSERVATIONS 
FROM  AN  AIRPLANE 

In  order  to  qualify  as  meteorologist  competent  to 
confer  with  aviators,  it  seemed  desirable  to  become 
personally  acquainted  with  some  of  the  conditions 
that  confronted  them.  As  a  matter  of  professional 
acquirement  therefore,  I  was  glad  to  accept  an  in- 
vitation to  go  aloft  after  the  necessary  official  ar- 
rangements had  been  made  with  Washington. 

This  trip  was  in  line  with  the  previous  endeavors 
of  applying  practical  meteorology  to  the  science  of 
flight  and  appropriately  extended  the  work  which  was 
begun  in  San  Diego  with  Chanute  and  the  sea-gulls 
fifteen  years  before. 

Object  of  Flight. — I  wished  to  put  myself  in  the 
student's  place  and  learn  at  first  hand  the  practical 
facts  he  demanded  from  weather  observations  and 
to  acquaint  myself  with  everything  possible  that 
might  be  of  value  to  an  aviator.  There  were  two 
definite  things  of  which  I  desired  knowledge:  first, 
to  determine  the  height  of  the  upward  trend  of  the 
sea-breeze  over  Point  Loma  which  causes  the  mys- 
terious "woolly"  of  a  score  of  years'  acquaintance 
from  a  yachting  standpoint;  second,  to  observe  the 
extent,  form,  and  composition  of  the  velo  cloud 
which  is  the  characteristic  sun-cover  of  California. 

Preparations  for  the  Ascent. — Aviator  Instructor 
Oscar  Brindley  (the  1915  winner  of  the  Curtiss 
trophy),  in  military  tractor  No.  50,  was  assigned 

(16) 


•>  Weather  Observations  Jrom  an  Airplane     17 

as  pilot.  It  may  be  stated  here  that  the  accepted 
definition  of  aviator  is  a  pilot  of  a  flying-machine 
heavier  than  air.  The  airplane  used  in  my  first 
flight  (see  Fig.  13)  was  made  in  Los  Angeles  and  is 
the  present  standard  army  model.  This  tractor  has 
an  8o-horsepower  engine  and  8-foot  propeller.  It  is 
21  feet  long,  has  a  wing-spread  of  38  feet,  supporting 
area  364  square  feet,  and  a  flying  radius,  with  two 
persons,  of  300  miles.  The  maximum  altitude  at- 
tained with  this  model  at  San  Diego  was  13,000  feet. 
Before  being  placed  in  service  the  machines  are 
thoroughly  gone  over  at  the  repair  shop  (see  Fig.  22), 
and  the  motors  are  run  at  full  speed  for  twenty-four 
hours,  after  which  they  are  taken  down  and  subjected 
to  scrutiny  for  possible  defects.  All  of  the  struts, 
guys,  and  wires  are  closely  examined;  the  boltheads 
are  all  drilled,  wired,  and  soldered  so  that  no  amount 
of  vibration  will  loosen  them.  Regardless  of  the 
length  of  the  flight,  each  machine,  before  going  up 
again,  is  given  a  rigid  inspection  and  not  until  the 
mechanicians  have  tested  every  part  is  it  pronounced 
ready. 

Not  being  prepared  with  a  regulation  aviation 
suit,  I  was  loaned  a  leather  jacket  by  one  officer,  face- 
goggles  and  safety  helmet  by  others.  I  then  took 
my  place  in  the  observer's  seat  forward  and  was 
strapped  into  it  with  the  safety  belt  (see  Fig.  12).  I 
was  cautioned  to  let  my  body  give  way  as  the  waist- 
controls  were  moved  from  side  to  side  and  not  pay 
any  attention  to  the  steering  rudder  wheel  which 
had  a  way  of  mysteriously  revolving,  advancing  and 
receding. 

In  cranking  an  airplane,  a  certain  formula  is 
always  gone  through.  The  mechanician  at  the  pro- 


1 8       The  Aviator  and  the  Weather  Bureau 

peller  calls  out,  "Close!"  The  aviator  closes  the 
switch  and  repeats  the  word.  This  short-circuits  the 
ignition  apparatus  so  that  no  spark  occurs  in  the 
cylinders.  The  propeller  is  turned  in  order  to  intro- 
duce explosive  mixtures  into  the  cylinders.  When 
ready  to  start  the  mechanician  says  "Open!"  The 
aviator  opens  the  switch  and  repeats  the  word.  The 
charges  in  the  cylinders  then  fire  when  the  propeller 
is  turned. 

After  the  engine  starts,  the  machine  is  "trimmed" 
by  helpers  and  jockeyed  for  a  favorable  "take-off" 
into  the  air.  (See  Figs.  14,  15.)  This  model  of  air- 
plane climbs  on  a  gradient  I  to  7;  its  minimum  speed 
is  41  miles  per  hour.  In  other  words,  if  the  speed  is 
less  than  41  miles  per  hour  the  machine  will  not  fly 
horizontally. 

The  Ascent. — The  tractor  was  headed  into  a  30- 
mile  northwesterly  wind  so  that  the  "take-off"  was 
quick  and  easy;  there  were  only  a  few  seconds  spent 
rolling  over  the  field,  when  the  airplane  left  the 
ground  and  I  felt  the  never  to  be  forgotten  cushioning 
feeling  of  the  air.  For  ten  seconds  there  was  experi- 
enced a  decidedly  weakening  nervous  chill,  which 
occurred  to  me  once  before  when  making  a  high  dive 
from  a  spring-board.  It  was  the  sort  of  physiological 
disturbance  that  can  only  be  counteracted  by  im- 
mediately pulling  one's  self  together  saying,  "Well, 
here  goes  nothing!"  The  momentary  depression  was 
immediately  followed  by  a  corresponding  elation  of 
feeling  which  strange  to  say  did  not  leave  me  during 
the  trip  and  is  always  associated  with  thoughts  of 
the  journey.  There  was  no  dizziness,  although  I  am 
peculiarly  susceptible  to  the  least  change  in  balance. 
The  earth  did  not  recede  as  we  progressed  steadily 


Weather  Observations  Jrom  an  Airplane     19 

upward;  we  seemed  part  of  the  earth,  but  not  of  it. 
Although  the  airplane  reached  an  altitude  of  3,000 
feet  in  a  comparatively  few  minutes,  the  barometer 
falling  from  30.0  to  27.0  inches,  the  decreased  bodily 
pressure  was  not  at  all  noticeable.* 

Next  to  the  supporting  quality  of  the  atmosphere 
I  had  noticed  the  yo-mile  blast  of  air  as  the  airplane 
pushed  its  way  steadily  onward  and  upward.  Natu- 
rally, the  exhaust  of  the  motor  in  addition  to  the  roar 
of  the  wind  made  conversation  impossible.  Some 
airplanes  have  telephone  communication  between 
observer  and  pilot.  (See  Fig.  9.)  During  one  flight 
in  a  machine  not  so  equipped,  the  passenger  noticed 
the  breaking  of  some  apparatus.  Knowing  that  it 
was  impossible  to  make  himself  heard  he  hastily 
scribbled  the  word  "Accident!"  on  a  bit  of  card, 
whereupon  the  pilot  shut  off  his  engine  and  glided 
to  earth. 

Two-thousand  Feet  above  Point  Loma. — Carrying 
out  my  suggestion  as  to  investigating  the  "woolly," 
the  pilot  drove  the  machine  straight  for  Point  Loma 
and  those  unseen  aerial  breakers.  Suddenly  there 
were  two  distinct  "wallops"  and  I  felt  the  fuselage 
beneath  me  respond  as  if  struck  by  a  stuffed  club. 
There  was  evidently  first  a  surge  then  a  drop,  and  it 
was  the  descending  current  of  air  that  deprived  the 
airplane  of  the  supporting  medium,  hence  the  shock. 
Point  Loma  itself,  from  this  altitude,  and  seen 
directly  from  above,  looked  very  like  a  barracuda's 
backbone — long,  low,  and  ugly.  Although  this  pen- 
insula (see  Fig.  21)  is  less  than  500  feet  high  it  so 
effectively  deflects  the  prevailing  northwesterly  wind 
that  the  upward  surge  has  been  noticed  by  aviators 

*Trans-American  CJ'.matic  Association,  1915,  31:20,  Hot  Springs,  Va. 


20       The  Aviator  and  the  Weather  Bureau 

at  an  altitude  of  4,000  feet.  It  is  no  wonder  then 
that  these  descending  winds,  called  "woollies"  (from 
their  churning  the  water  into  isolated  masses  which 
look  like  tufts  of  wool),  are  dreaded  alike  by  yachts- 
men and  birdmen.  They  have  been  known  to  carry 
away  topsails  from  too  closely  venturing  schooners 
and  student  aviators  always  give  the  vicinity  of 
Point  Loma  a  wide  berth. 

No  Winds  Aloft. — We  had  not  changed  our  direc- 
tion since  leaving  the  ground,  but  after  passing  over 
Point  Loma  the  airplane  was  put  sharply  on  a  port 
course.  I  had  been  expecting  this  and  must  confess, 
somewhat  dreaded  it,  innocently  thinking  that  a 
3O-miIe  wind  added  to  our  yo-mile  rate  of  speed 
would  "heel"  the  craft  to  an  uncomfortable  angle 
when  the  course  was  changed  from  northwesterly  to 
southerly.  What  was  my  astonishment  to  find  that 
the  putting  about  was  unaccompanied  by  any  of 
the  nautical  motions  such  as  tilting  or  canting.  Theo- 
retically one  may  be  ever  so  well  grounded  in  physical 
laws  but  it  seems  to  take  actual  experience  to  bring 
their  truth  home  to  us.  Of  course  there  can  be  no 
wind  in  the  air;  when  we  entered  the  air  it  was 
moving  30  miles  an  hour  in  relation  to  the  earth 
but  as  soon  as  we  were  free  from  the  earth  the  veloc- 
ity of  the  wind  had  no  effect  on  our  flight.  No 
matter  how  strong  the  gale,  so  far  as  it  concerned 
the  airplane,  if  the  wind  be  steady  no  difficulty  is 
experienced;  the  aviator  is  concerned  only  by  wind- 
shifts. 

The  Velo  Cloud  Seenjrom  Above. — In  kindergarten 
days  I  remember  that  one  of  the  first  questions  I  asked 
was  "Are  clouds  smoke?"  And  this  early  query  was 
really  first  answered  in  the  air.  Fog  on  a  mountain 


Weather  Observations  from  an  Airplane     21 

top  may  be  cloud,  but  somehow  cloud  free  from  close 
proximity  to  the  earth  seems  different. 

The  machine  was  put  through  the  cloud  blanket 
much  as  a  horse  takes  a  hurdle;  it  seemed  unlike 
fog  and  more  of  a  palpable  substance.  As  we  emerged, 
the  sun  was  shining  on  it  like  a  silvery  sea  with 
gently  undulating  surfaces  and  it  looked  for  all  the 
world  as  supportable  as  layers  of  cotton-wool.  Many 
times  have  cloud-banks  from  mountain  tops  been 
observed,  yet  the  upper  side  of  the  velo  cloud  from 
a  flying-machine  looked  very  different.  The  cloud 
was  only  four  or  five  hundred  feet  thick  and  extended 
inland  a  few  miles  in  irregular  outline.  The  seaward 
edges  of  the  velo  cloud  were  not  ragged,  and  appar- 
ently paralleled  the  coast  for  10  or  15  miles. 

Such  was  the  exhilaration  and  confidence  the  air 
gave  that  I  can  understand  how  parachute  jumpers 
confidently  step  off  into  space,  for  to  them  the  air 
is  a  supporting  medium  no  more  terrible  than  a 
transparent  sea  to  a  good  swimmer.  I  believe  that 
the  record  parachute  drop  was  made  in  1916  by 
Colonel  Maitland,  of  the  English  Royal  Flying 
Corps,  who  descended  in  a  parachute  10,000  feet 
from  an  airplane.  Fifteen  minutes  was  occupied  in 
the  descent. 

Ease  of  Vision  at  3,500  Feet  Altitude. — At  this 
altitude  the  ease  of  vision  is  most  remarkable.  At 
this  height,  with  perpendicular  vision,  the  eye  is 
possessed  of  wonderful  powers.  In  those  "solitudes 
august  with  stars"  men  not  only  "mount  up  with 
wings  as  eagles"  but  are  given  the  eagle's  unob- 
structed vision.  Birds  have  been  credited  with  much 
too  keen  vision.  From  this  height  of  several  thousand 
feet  every  object  stood  out  with  remarkable  distinct- 


22       The  Aviator  and  the  Weather  Bureau 

ness.  Automobiles  racing  along  the  El  Cajon  boule- 
vard to  Lakeside  were  readily  picked  up  with  the 
unaided  eye  although  20  miles  away.  Looking  down 
over  the  aviation  field  the  long  compass  mark  and 
the  wind-direction  pennant  (Figs.  19  and  20)  were 
easily  distinguished.  The  bay  and  ocean,  however, 
gave  the  most  remarkable  revelation,  for  the  bottom 
of  the  bay  and  the  shallow  ocean  shore  were  plainly 
discernible.  The  absence  of  water  as  well  as  air 
refraction  explains  why  submarines  cannot  hide 
from  an  airplane:  one  of  the  army  aviators  told  me 
that  a  submarine  cannot  ordinarily  sink  so  low  that 
it  cannot  be  seen  from  an  airplane. 

Color  of  Landing-ground  Important. — Owing  to 
the  absorption  and  reflection  of  sunlight,  there  is  a 
distinct  variation  in  the  character  of  otherwise  simi- 
lar landing-ground.  A  field,  dark  from  recent  plowing 
(or  burning),  will  heat  the  air  over  it  faster  than  will 
a  field  of  stubble,  hence  over  the  former  field  there 
will  be  the  greater  air  disturbance,  and  this  will 
affect  the  ease  of  landing.  Air  is  heated  by  contact 
and  convection.  One  pi  the  aviators  said  that  re- 
cently he  was  descending,  and  had  all  but  reached 
the  ground  when  a  localized  conventional  current 
hurled  his  machine  upward  some  distance  but  im- 
mediately afterward  deposited  him  on  the  ground 
without  damage. 

Spiraling  Down  3,000  Feet. — Speeding  ever  in  wide 
circles  the  course  lay  southeast  over  the  upper  part 
of  San  Diego  Bay.  The  city  of  San  Diego  presented 
the  usual  checkerboard  appearance  (Fig.  16),  and 
even  at  this  altitude  it  would  seem  easy  to  drop  an 
orange  at  almost  any  point.  The  velp  cloud  was 
lifting  and  we  could  see  the  gradual  disappearance 


Weather  Observations  from  an  Airplane     23 

as  it  melted  rather  than  drifted  from  North  Island. 
(See  Fig.  17.) 

The  gliding  descent  was  made  from  an  altitude  of 
2,500  feet,  starting  above  San  Diego.  As  the  aviation 
school  was  approached,  we  could  see  a  number  of 
machines  in  the  air,  three  below  and  two  above  us, 
circling  about  like  hawks.  ^  And,  like  soaring  birds, 
these  machines  had  their  air-lanes,  designated 
courses  and  levels  being  devoted  to  the  different 
classes  of  machines.  The  landing  was  made  without 
incident  and  the  hour's  flight  was  ended. 

Outline  of  Meteorological  Work  at  the  Aviation 
School — At  the  close  of  the  lecture  detail,  the  atten- 
tion of  the  student  aviators  was  called  to  the  impor- 
tance of  their  having  as  thorough  knowledge  as  pos- 
sible of  the  fundamentals  of  meteorology.  The  appli- 
cation of  these  fundamentals  to  the  analysis  of  air 
conditions  met  with  in  their  daily  flights  was  shown 
to  be  essential.  Investigations  as  to  varying  wind 
direction  were  taken  up  by  one  of  the  staff  instructors 
by  the  use  of  small  parachutes  to  be  dropped  at 
different  altitudes.  (See  Fig  ^  8.)  Through  the 
cooperation  of  the  local  official  in  charge  of  the  San 
Diego  Weather  Bureau  station,  duplicate  signal 
sheets  were  available  from  which  the  student  officers 
made  their  local  weather  maps.  From  these  maps 
and  their  own  flights,  they  could  arrive  at  some  rela- 
tionship between  the  actual  and  the  theoretical  3,000- 
and  io,ooo-foot  level  maps  prepared  from  the  Bige- 
low  formula,  as  used  by  the  Bureau.  Lectures  were 
given  on  temperature  and  its  distribution;  winds, 
moisture,  and  clouds  were  also  made  part  of  the 
course,  one  of  the  papers  of  the  Bureau*  being  re- 

*"CIouds  of  California,"  Carpenter,  1914,  24,  zd  ed.,  Ft.  Leaven- 
worth  (U.  S.  Army  Press). 


24       The  Aviator  and  the  Weather  Bureau 

printed  by  the  aviation  school  by  permission  of  the 
Chief  of  the  Bureau  and  used  as  a  textbook.  The 
Weather  Bureau  furnished  the  station  with  a  stan- 
dard set  of  meteorological  instruments  so  that  the 
student  officers  could  become  perfectly  familiar 
with  the  regular  equipment  at  the  Weather  Bureau 
stations. 

Extending  the  Usefulness^  of  the  Bureau  to  the 
Aviators. — Practical  utilization  by  the  aviators  of 
this  district  of  the  information  possessed  by  the 
Bureau  has  received  considerable  impetus  during  the 
past  six  months.  During  the  cross-country  flights 
of  April  and  May,  1916,  the  Los  Angeles  station  was 
directed  by  the  Chief  of  Bureau  to  furnish  weather 
and  flight  conditions  between  San  Diego  and  Los 
Angeles.  With  the  aid  of  the  general  weather-map 
data  from  the  regular  stations,  and  special  observa- 
tions of  wind,  weather,  and  fog  conditions  on  the 
immediate  coast  near  Los  Angeles,  and  on  Mount 
Wilson,  it  was  possible  to  issue  satisfactory  forecasts 
of  flying  conditions.  The  eye-observations  of  fog- 
heights  as  determined  by  the  Weather  Bureau  co- 
operative station  at  the  Mount  Wilson  Solar  Obser- 
vatory were  especially  valuable.  From  this  moun- 
tain (6,000  feet  elevation)  it  is  possible  on  a  good  day 
to  see  the  whole  length  of  the  coast  from  Point  Fir- 
min,  San  Pedro  harbor  to  Point  Loma,  San  Diego 
Bay.  Knowing  different  levels,  the  observer  at 
Mount  Wilson  was  able  to  give  actual  thickness  and 
extent  of  the  fog-belt  and  its  past  twenty-four-hour 
history. 


CHAPTER  IV 
INVESTIGATING  THE  UPPER  AIR 

Balloon  Soundings  into  the  Stratosphere. — It  was 
the  writer's  privilege  to  be  present  when  some  highly 
interesting  and  instructive  experiments  made  by  the 
Weather  Bureau  in  cooperation  with  the  Smithsonian 
Institution,  in  sounding  the  upper  air  were  made  at 
Avalon,  Santa  Catalina  Island,  off  the  coast  of  south- 
ern California  in  July  and  August,  1913.*  The  results 
of  this  work  were  in  close  agreement  with  similar 
soundings  of  the  upper  air  throughout  other  surveyed 
portions  of  the  earth's  atmosphere,  and  a  record 
ascension  for  this  country  was  made  on  July  30 — 
32,643  meters  or  20^2  miles.  In  common  with  other 
observations  of  temperatures  in  the  stratosphere, 
the  minimum  temperature  of  these  soundings  (-90  F., 
August  3)  was  registered  within  the  first  10  miles. f 

Of  especial  interest  to  the  aviator  is  the  table  on 
the  next  page  which  shows  wind  velocities  increasing 
with  elevation  as  determined  by  observations  of  the 
Avalon  balloons. 

*University  of  California  Chronicle,  1915,  17:1-25,  Berkeley. 
fMonthly  Weather  Review,  1914,  42:410,  Washington. 


1 


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§>  8 


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(26) 


Investigating  the  Upper  Air  27 


Charts  Showing  Upper-air  Weather  Conditions. — 
It  is  believed  that  the  following  charts  when  exam- 
ined in  connection  with  the  accompanying  expla- 
nation in  the  text  will  give  the  reader  something  of  an 
outline  as  to  the  conditions  existing  in  the  upper 
regions  of  the  atmosphere. 


CHART   NO.   I 

Horizontal  Projections  of  the  Paths  of  the  Sounding 

Balloons  Liberated  at  Avalon,  California, 

July  23  to  August  iOy  1913 

Reproduced  from  the  Monthly  Weather  Review,  42:  423 


This  figure  shows  the  horizontal  projections  as   far  as  the  balloon 
bserved,  not  the  entire  distance  traveled  until  it  landed. 


was  observed, 


(28) 


KILQM 

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CHART    NO.    2 

Vertical  Temperature  Gradient,  Avalon, 
California,  July  27,  1913 

Solid  line  represents  the  ascent  of  the  recording  apparatus,  the  dotted 
line  the  descent.    (Verticals  25°  C.  or  45°  F.) 

Reproduced  from  the  Monthly  Weather  Review,  42:  412 

(29) 


ALTITUDE 
KILOMFTERS 

37 


30 
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28 
27 
26 
25 
24 
23 
22 
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CEHTIGHADE 


CHART    NO.    3 

Mean  Vertical  Tem- 
perature Gradient 

Figure  reproduced  from 
Monthly  Weather  Review. 
42:  413- 

Altitude  values  are  in 
kilometers  at  the  left,  and 
in  miles  at  the  right.  Tem- 
perature values  are  in  Cen- 
tigrade at  bottom,  in  Fah- 
renheit at  top. 


Maximum   airplane   alti- 
tude 26,242  feet  or  5  miles. 


(30) 


9 

METERS 

5000 
4500 
4000 
3500 
3000 
2500 
2000 
1500 
IOOO 

m/s 

n 

'     13    K 

\ 

18 

20 

22 

MHesperHour 
FEET 

17,000 
74,000 
//,000 
8,000 

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> 

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S     6    7     S    9     /< 

CHART    NO.    4 

Diagram  Showing  Increase  of  Wind  with  Elevation 
Data  from  Eight  Meteorographs 

From  the  article  "Free  Air  Data  in  Southern  California,  July  and 
August,  1913"  by  Dr.  Wm.  R.  Blair,  Professor  of  Meteorology,  m  the 
Monthly  Weather  Review,  for  July,  1914,  it  is  learned  that  the  wind  shifts 
from  west  to  east  rather  abruptly  at  16  to  20  km.  (10  to  12  miles);  below 
this  level  down  to  about  5  km.  (3  miles)  it  is  quite  uniformly  from  the 
west.  Extremes:  Maximum  wind  velocity  21.2  miles,  5,000  meters 
elevation,  5  P.M.,  July  24;  minimum  wind  velocity  O.8  miles,  1,500  meters 
elevation,  5  P.M.,  July  27. 

The  table  shows  a  steady  increase  in  velocity  of  the  wind  with  elevation, 
the  data  being  obtained  from  the  eight  meteorographs.  There  were  four 
morning  flights  (July  31,  August  3,  7,  8)  and  five  afternoon  flights  (July 
24,  27,  August  3,  7,  8,  1913),  and  elevations  were  computed  for  nine 
heights,  1,000  to  5,000  meters.  Beyond  the  5,000  meters  the  records  show 
that  from  2  to  7  miles  altitude  the  wind  increases  at  approximately  the 
same  rate  that  the  density  of  the  air  decreases. 

(31) 


100 


300 


too 


;|  1  «  « 


CHART   NO.    5 

Showing  Number  of  Flights  and  Duration  in 
Hours  for  the  Months  of  July  to  December, 


and  January  to  August,  1916 

Prepared  by  the  War  Department,  Signal  Corps  Aviation  School,  San 
Diego,  California,  and  furnished  through  the  courtesy  of  Col.  W.  A. 
Glassford,  Signal  Corps,  U.  S.  Army,  Commanding  Officer,  September 
14, 


(32) 


FIG.  I.    CONGRESSIONAL   MEDAL   AWARDED  WRIGHT    BROTHERS 

(Designed  by  Morgan) 

This  medal  was  awarded  Orville  and  Wilbur  Wright  by  resolution  of 
Congress,  March  4,  1909-    Bronze  replica  in  possession  of  the  writer. 
Photographed  May  31,  iQi6,  by  permission  of  the  Director 
of  the  Mint,  Philadelphia 

(33) 


FIG.  2.    ASCENT  OF  SOUNDING-BALLOONS  AT  AVALON 

Photographed  July  27,  1913 

This  set  was  liberated  from  the  base  of  the  U.  S.  Weather  Bureau, 
Avalon,  Catalina  Island,  California,  at  4.57  P.M.,  July  27,  1913,  and  rose 
to  a  height  of  23,870  meters  in  one  hour  and  three  quarters  when  one  of 
the  balloons  burst  and  the  descent  began.  This  was  observed  by  Carpenter 
at  the  theodolite. 

(34) 


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FIG.  3.    METEOROGRAPH  WHICH   MADE  THE  ASCENT 

OF  JULY  27,    1913 
Photographed  August,  1913 

This  meteorograph  rose  to  a  height  of  23,870  meters  (94,716  feet),  at 
which  height  the  pressure  was  23  mm.  (0.906  inches),  temperature— 52.1  C 
(-58  F.),  relative  humidity  21  per  cent,  wind  E.  (or  more  precisely  S.  79 
degrees  E.),  velocity  6.1  m.p.s.  (14  miles  per  hour),  but  the  minimum 
temperature  was  registered  at  15, 228  meters  (49,960  feet)  when  the  thermom- 
eter showed  -64.7  C.  (-85  F.),  at  which  time  the  pressure  was  89  mm. 
(3.504  inches  of  the  barometer),  relative  humidity  19  per  cent,  wind  N.W., 
3.4  m.p.s.  (8  miles  per  hour). 

The  basket  was  picked  up  at  sea  off  Oceanside,  San  Diego  County, 
about  90  km.  (145  miles)  east  of  Ayalon. 

For  the  first  6  miles  of  ascension  the  balloon  moved  upward  at  the 
rate  of  8  miles  per  hour. 


(35) 


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FIG.  6.    TYPE   OF  AIRPLANE  USED  IN    1911  ON    NORTH    ISLAND 
Photographed  October,  IQII 

This  photograph  of  Mr.  Glenn  Curtiss  in  his  "pusher"  airplane  was 
made  shortly  after  the  Curtiss  School  of  Flying  was  established  in  1911, 
on  North  Island.  At  his  right  is  Local  Forecaster  Carpenter. 

Comparison  of  this  machine,  which  four  years  ago  was  the  last  word 
in  airplanes,  with  the  tractor  shown  on  the  opposite  page,  indicates  the 
rapid  progress  in  design. 


(38) 


FIG.  7.    DISCUSSING  A  FLIGHT 
Photographed  October  18,  igi  f 

Aviation  Instructor  Oscar  Brindley  discussing  a  flight  with  Captain 
Clarke,  U.  S.  A.,  and  other  officers  at  the  U.  S.  Aviation  School  at  San 
Diego. 

Mr.  Brindley  is  standing  by  the  side  of  Captain  Clarke  in  the  group  at 
the  right.  After  every  flight  the  Instructor  reviews,  point  by  point,  the 
features  of  the  flight,  showing  the  pupil  his  deficiencies  and  explaining  how 
he  may  avoid  them  in  the  future. 

The  officer  at  the  left,  Lieutenant  Brown,  has  the  regulation  leather 
leggings,  coat  and  helmet,  and  is  ready  to  go  up  as  soon  as  the  mechanicians 
(who  may  be  seen  at  the  extreme  left)  finish  inspection  and  pronounce 
the  airplane  fit  for  the  next  flight. 


(39) 


FIG.  8.    CAPTAIN  CULVER  AND  PARACHUTE 
Photographed  October  21,  iQif 

Captain  C.  C.  Culver,  U.  S.  Cavalry,  Adjutant,  Aviation  School,  with  a 
parachute  in  his  hand,  having  word  with  Captain  L.  W.  Patterson, 
U.  S.  A.,  before  the  latter's  flight.  The  object  of  the  parachute  is  to 
determine  changing  wind-direction  at  different  heights. 

The  airplane  wireless  record  is  now  held  by  Captain  Culver.  In  October, 
1916,  he  sent  a  message  119  miles  from  Santa  Monica  to  San  Diego,  Cali- 
fornia, while  flying  at  an  altitude  of  i  Yi  miles.  He  received  a  radio  message 
from  a  distance  of  1 1  miles  while  flying  7,000  feet  aloft.  He  is  also  the  first 
military  aviator  to  rig  up  two  airplanes  so  that  they  could  exchange 
messages  while  in  flight.  The  radio  set  used  weighed  less  than  forty-five 
pounds. 


(40) 


FIG.  9.    LIEUTENANT  GORRELL,   U.  S.   INFANTRY,  AS  OBSERVER 
Photographed  October,  1915 

The  noise  of  the  motor,  together  with  the  terrific  blast  of  air,  makes 
conversation  impossible  between  the  pilot  and  observer;  for  that  reason 
telephones  are  sometimes  installed  as  noted  in  this  photograph. 

Lieut.  Edgar  S.  Gorrell  is  shown  as  the  observer  in  this  photograph. 
He  has  since  qualified  as  an  aviator  and  made  a  brilliant  record  in  the 
Mexican  activities  in  1916. 


(41) 


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FIG.  18.    MILITARY  TRACTOR  No.   50  AT  3,500  FEET  ALTITUDE 
Photographed  October  20,  1915 

The  airplane,  in  which  the  pilot,  Oscar  Brindley  and  the  observer, 
Meteorologist  Carpenter,  made  their  flight,  was  photographed  at  the 
maximum  elevation,  3,500  feet  above  the  aviation  field. 


(50) 


FIG.  19.   FLYING  SQUAD'S  WIND-DIRECTION  PENNANT  ON  TOWER 

Photographed  October  5,  /p/5 

The  regular  observation  tower  from  which  all  observations  and  notes 
on  every  flight  are  made  is  just  back  of  the  headquarters  building.  The 
station  anemometer  is  on  the  tower,  and  the  portable  anemometer  is  to 
the  left. 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
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THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
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OVERDUE. 


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